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Modbus I/O Server


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I have been successful in communication with a Delta PLC using Modbus library support & even built some projects using this method of communication with more than one PLC.

What I want to be able to do is to use the 'Modbus I/O Server' to set up the elements in my project & not have to use the Modbus function or code fragment that I have used before. Please also clarify the following.

1. The thing should work with just the Modbus I/O server & a VI

2. It should also work with DSC

I am having major problems regarding both these areas. While there is a lot of stuff out there & some 'very high level' opinions on what to do, it leaves me none the wiser about how simply go along & get a simple data exchange from a PLC using ethernet modbus & set up an alarm function to it with the DSC module.

I have used LV to develop a project with many I/O's & a lot of simulation. Understand most of the structures & tricks about getting data around

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Hi Monti,

The biggest barrier for most people to the modbus IO server is that you have to have the DSC module. But if you do have it the it makes modbus much simpler and you get the features such as alarming.

The best thing I'd suggest is give it a go. If you don't have it already download a trial of DSC and follow some of the examples.



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Hi James,

Thanks a lot for replying. I do have the DSC module. I 'm a bit confused as regards how it all fits together.

What I have done previously was to use the 'Modbus library' functions & write out an app for conencting to the PLC's. This works fine though I have the task ( cumbersome ) of defining the Modbus commands, length of registers to be read etc & then use a shift register approach to switch between the MOdbus commands.

What I was hoping for in the Modbus I/O server was to be able to define all this during the creation of the I/O server & be absolved of it all later on. This is typically what you do when using other SCADA systems. I'm sure this will work with LV as well but can't seem to peice it together.

Many thanks.

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  • 4 years later...
13 hours ago, Meriem Ait said:


I'm trying to connect labview with a datalogger using modbus but i don't have the modbus in the version of labview that i have.

LabVIEW does not ship with Modbus communication. That feature is part of the Data Supervisory and Control module (DSC). There is the Plasmionique Modbus MasterĀ  in the download section that may do what you're needing (I've not used it) and the NI Modbus code on the NI website.

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